1. Field of the Invention
The present invention relates to an electronic device and a method for producing the electronic device.
2. Description of the Related Art
Electronic devices such as field-effect transistors and condensers (capacitors) are generally equipped with at least two electrodes with an insulating film interposed between the at least two electrodes. Such electronic devices such as thin film transistors or the like have been applied to flat panel displays (FPDs) employing liquid crystal elements, organic electroluminescence elements (hereinafter, referred to as “organic EL elements” in some cases) in which a thin film material that emits light by excitation due to application of an electric current is used, or the like; X-ray sensors; or the like.
An electronic device is generally formed by forming a first electrode on a substrate and then providing a second electrode on the first electrode with an insulating film interposed between the first electrode and the second electrode. When the electronic device is a bottom-gate type field-effect transistor, the first electrode functions as a gate electrode, and the second electrode functions as a source electrode and a drain electrode. Mo (molybdenum) is used as a constituent material of the first electrode in consideration of adhesion between the first electrode and the insulating film that is disposed on the first electrode (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2007-250982).
In the electronic device, the first electrode and the second electrode are electrically separated by the insulating film. However, there are cases where a leak current occurs between the first electrode and the second electrode. Since the occurrence of the leak current causes deterioration in electronic device characteristics, attempts for suppressing the leak current have been made.
As a method for suppressing the leak current, a method of adjusting the taper angle of an edge cross section of the first electrode to an angle of a degree being possible to suppress the leak current is described. This method aims for improving the adhesion between the first electrode and the insulating film by adjusting the taper angle of the edge cross section of the first electrode to be as small as possible, thereby suppressing the occurrence of cavities or cracks in the insulating film in the neighborhood of the edge of the first electrode, and suppressing the leak current.
However, when the first electrode includes Mo, it is difficult to adjust the taper angle of the edge cross section of the first electrode to an angle of a degree being possible to suppress the leak current. Further, when the first electrode includes Mo, while it depends on the method of forming an insulating film employed, a covering property of the insulating film with respect to the taper portion of the first electrode may be considerably deteriorated, cavities or cracks in the insulating film in the neighborhood of the edge of the first electrode may occur and, as a result of which, the leak current may further increase.
As another method for suppressing the leak current, JP-A No. 2008-219008 discloses to employ an insulating film having a two-layer configuration of a layer including SiO2 and a layer including SiN. However, according to the technology disclosed in JP-A No. 2008-219008, the layer configuration of the insulating film should be changed (to have a two-layer configuration) in order to suppress the leak current, whereby it may cause complication in the configuration or manufacturing processes.